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Avoid divide by zero and NaNs in scale_array_elements_to_u64

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Patch from teor; part of 13104
This commit is contained in:
Nick Mathewson 2014-09-10 23:59:21 -04:00
parent 5126bc2ebd
commit 59f9a5c786
2 changed files with 30 additions and 2 deletions
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5
src/or/routerlist.c
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@ -1802,7 +1802,7 @@ scale_array_elements_to_u64(u64_dbl_t *entries, int n_entries,
uint64_t *total_out) uint64_t *total_out)
{ {
double total = 0.0; double total = 0.0;
double scale_factor; double scale_factor = 0.0;
int i; int i;
/* big, but far away from overflowing an int64_t */ /* big, but far away from overflowing an int64_t */
#define SCALE_TO_U64_MAX (INT64_MAX / 4) #define SCALE_TO_U64_MAX (INT64_MAX / 4)
@ -1810,7 +1810,8 @@ scale_array_elements_to_u64(u64_dbl_t *entries, int n_entries,
for (i = 0; i < n_entries; ++i) for (i = 0; i < n_entries; ++i)
total += entries[i].dbl; total += entries[i].dbl;
scale_factor = SCALE_TO_U64_MAX / total; if (total > 0.0)
scale_factor = SCALE_TO_U64_MAX / total;
for (i = 0; i < n_entries; ++i) for (i = 0; i < n_entries; ++i)
entries[i].u64 = tor_llround(entries[i].dbl * scale_factor); entries[i].u64 = tor_llround(entries[i].dbl * scale_factor);

27
src/test/test_dir.c
View File

@ -1749,10 +1749,37 @@ test_dir_scale_bw(void *testdata)
tt_assert(total <= (U64_LITERAL(1)<<62)); tt_assert(total <= (U64_LITERAL(1)<<62));
for (i=0; i<8; ++i) { for (i=0; i<8; ++i) {
/* vals[2].u64 is the scaled value of 1.0 */
double ratio = ((double)vals[i].u64) / vals[2].u64; double ratio = ((double)vals[i].u64) / vals[2].u64;
tt_double_op(fabs(ratio - v[i]), <, .00001); tt_double_op(fabs(ratio - v[i]), <, .00001);
} }
/* test handling of no entries */
total = 1;
scale_array_elements_to_u64(vals, 0, &total);
tt_assert(total == 0);
/* make sure we don't read the array when we have no entries
* may require compiler flags to catch NULL dereferences */
total = 1;
scale_array_elements_to_u64(NULL, 0, &total);
tt_assert(total == 0);
scale_array_elements_to_u64(NULL, 0, NULL);
/* test handling of zero totals */
total = 1;
vals[0].dbl = 0.0;
scale_array_elements_to_u64(vals, 1, &total);
tt_assert(total == 0);
tt_assert(vals[0].u64 == 0);
vals[0].dbl = 0.0;
vals[1].dbl = 0.0;
scale_array_elements_to_u64(vals, 2, NULL);
tt_assert(vals[0].u64 == 0);
tt_assert(vals[1].u64 == 0);
done: done:
; ;
} }